I've now used the MBP sitting on my lap and worked with it comfortably for about 2 hours and I didn't even need to use the Belkin Cooling Pad I bought, though I do still use that every once in a while.
The overall performance of the machine has been excellent and—as I mentioned earlier—I love the display. The battery life from the machine has been very good for me and after a couple of hours on battery with moderate use I'm down to about 45% of my battery charge remaining.
One of the things I didn't appreciate until the last couple of days is the way the display adjusts to the ambient light. When you combine that with the backlighting on the keyboard the MBP is a completely useable machine in very low light conditions.
The quality of sound from the MBP is also a big improvement over my MacBook or any of the HP or Dell laptops I've had recently. If I have a video or piece of music that I want to share with the family then everyone can hear it quite easily.
About the only thing I didn't quite understand on my MBP was the purpose of the ExpressCard slot on the side of my machine. It's a slick looking little slot with a door that pushes in and smoothly rounded edges. I figured it must be a Mac thing so I did a little research on it.
Turns out the ExpressCard slot is the 34mm version of the PCMCIA card that PCs have had forever. The more traditional format—54mm—is what you tend to see in larger PC based laptops. If you're interested in reading about what this stuff is all about Extreme Tech covered the announcement of this new standard. Five years ago. Still, it's a worthwhile read if you want to understand what this is about.
So what exactly can you plug into this? With USB 2.0 and Firewire 800 there's not a lot you really need out of ExpressCard that isn't more easily handled with a simple external connector. The most popular devices that I found from NewEgg appear to be external SATAII interfaces that provide full 3.0Gps rates.
I can see that a memory card reader—something I wish Apple had just included on the machine—is an option, the Compact Flash format my Canon DSLRs use are too large to fit in the slot. There is a CF reader from Verbatim that fits into the ExpressCard/34 slot but it sticks out a bit. On the bright side it claims to be up to 5x faster than a USB based device. When I transfer photos from a nearly full 4GB CF card that may come in handy.
If you know of a killer ExpressCard use or have experience with it compared to comparable USB based devices (like CF card readers) please comment about it! I would be really interested in finding out if people are getting considerable performance gains using this technology.